engineerbob

I just rented a Specialized Fatboy for a couple of hours. Damn, that was fun. On several levels it reminded me of when I rode a "banana bike" as a kid.

Mostly, I rode it on snow-covered (2" - 4") singletrack in the forest. Although it was set up with 5 psi in the tires, any snow deeper than 3" presented a challenge. I'll want to rent it again in a few months after the snow has cleared, and try it on dry trails. And with soft tires I cannot see the need for suspension.

It wasn't bad on pavement, but I wonder how it would compare to my old Stumpjumper for more than a few miles. I may need to re-think my next MTB purchase.

Bob

Jseis 

As I ride my fatbike in nearly 100% sand and found it a tough go in some types of sand I decided to play around with the air pressure. I'm currently running 4 psi in the back and 3.5 psi in the front. This gives the back a bit more squash (one slight wrinkle) and I was interested in just what that means and the consequence of it.

I did a static loaded test to get a sense of the foot print. My H-Billies are 4.2, they squash with my 198 pounds and 31 pounds of bike (at the current air pressure above) to 4" wide (outside knobs) and 9" long (to the end of each taper of the squashed tire). What does this all mean?

After fiddling around with a weight bias of 60% back 40% front and studying the squash print I concluded that I'm at a total of 60 square inches and almost equally split front to back. The rear loading works out to ~4.5 pounds per square inch and the front is ~ 3.0 pounds per square inch. What does that mean? I can ride on almost any winter dune area and soft sand area pretty easily (easy is a relative term). This is ground that would be difficult for nearly any another tire to roll over without digging in and giving enormous resistance. It only takes an inch or two of sinking into the ground before you'll notice. When I was at 8 psi air pressure back and 6 psi air pressure front, it was real work to pedal the softer sand areas.

The beach does have one area at low tide that is very hard and smooth and a 3/4 ton truck will barely compress the sand and same true for a fat tire. There I could run at 10 psi quite handily but the minute I turn up the beach and enter the softer areas, the more difficult it becomes. The penalty one pays for switching to a paved trail is enormous, like trying to drive a tractor with low ground pressure tires, great at low speeds on farm roads, but once you hit the highway, it just takes more energy and bounces the crap out of you.

The physical energy needed to pedal through soft sand is pretty enormous but I find that I can ascend the 15% dune slopes quite handily if I pick a traverse line and keep the weight back. The squashed tire has excellent traction. When I crest a dune and go down it the bike takes right off down the slope, pretty amazing.

My take is that fat bikes are unique terrain bikes; Principally snow, sand, soft turf, plowed/disced/harrowed fields (depending on soils), playa lakes, salt pans, and etc. I've used ag equipment (Google Rolligon and study THAT LGP stuff!) that had lower pressure, but then I couldn't carry it out when I got stuck). An MIA1 Abrahams tank is rated at about 15 psi ground pressure (but then again, they've got 1000 horsepower).

bicyclelove

I got my first flat with the fatty today. I was riding a local trail, my favorite one in the summer, full of tight turns, rocks and stumps. I heard the rear tire pop off the edge of a rock and a few meters later the tire came right off the rim. Well being the Boy Scout I an I didn't have a spare tube, patch kit or pump I also found out that the bike won't roll with the tire off the rim. So I ended up carrying it back to my Jeep about 1/2 mile through the woods to the road. At least I still got my workout for the day
now I'm going to check out some kind of bag to attach to the bike to carry the stuff I will need. I could use a backpack but I hate riding with those. Does anyone have a good suggestion for a bag that can carry a tube etc. plus maybe some spare clothes for changing conditions. (Another thing I have found, the weather is never the same at the start and end of the ride)

SHOFINE

Yeah, I hate backpacks too! When I travel less than 10 miles I carry 5 CO2 cartridges & inflator plus tube in my Jandd Saddle bag. Longer trips I will also use my medium Ibera bag for other stuff and my Lezyne high volumn pump. The medium fits my frame perfect but you can get the large for sure.

Amazon.com : Ibera Bicycle Triangle Frame Bag : Sports & Outdoors

jdswitters

Second the Ibera bag, had mine for a year now. A patch kit, CO2 and a cable lock live in there. The zipper has turned out to be more water resistant than the outside pocket on my seattle sports panniers. I wouldn't take it camping, but its great for short trips around town.

Jseis 

Going to 32-22 on the front to take on sand..dunes. Oh the joy . Next...wolftooth.

engineerbob

I just bought a used 2015 Mukluk 3 off of C/L. It needs nothing other than me riding it.

Bob

Pic

+1.
While I don't have a fat bike (yet), I really appreciate your motivation.
If I do anything on a bike, or gym, it's to get a good workout in. No matter what bike I'm on, I push myself.
I don't anticipate trying to go lightest on a FB as it would rob me of a quality workout. That's not to say I am looking for the heaviest FB either.

Hypno Toad

On pavement, my Pugsley is slower than my Marin Nail Trail (converted to SS). I did some personal average speed analysis using a Strava segment - Pugsley 12.5 mph versus Nail Trail 14.2 mph. And yet, I ride the Pugsley almost every day in the winter - except in icy conditions since the Nail Trail has studded tires and the Pugsley doesn't. The fatbike is just that much fun to ride, on roads, on trails, on frozen lakes, on sandy beaches, ... you get the point

* Strava segment - Twisty - is 1.4 miles with hills and sharp turns, I ride this segment almost every day coming home from work.

Hypno Toad

Let's talk about fatbike flats: tubes versus tubeless.

My Pugsley has had two flats in two rides (front then rear). First one was a thorn, second one is TBD (haven't had time to pull it apart yet). I've seen comments that tubeless is the way to go, minimizes flats. I've always used tubes and know nothing about going tubeless. Let me know if you've gone tubeless on a fatbike, what is your experience and what do I need to make the conversion. Thanks!

Jseis 

Here's a good tubeless conversion update:

Tubeless Fatbike Conversion Update | Cycles In Life

Hypno Toad

Thanks! Very interesting, it'll take some additional thought (and additional flats) to get me to make the conversion.

Jseis 

The beach I ride is low flat risk...though the occasional buried piece of wood with nail can appear. The above link seemed to be the lightest most effective approach. However, I'd like to try it & see what it's like. With my current lightweight tubes & tires... probably a wash on weight.

Jseis 

Hey toad, what psi you rolling at to 12.5-14.2 speed and is that on snowy streets?

Hypno Toad

The road conditions vary for both bikes, including: dry, wet, snow, icy, windy, etc. The analysis is covers a total 75 rides; the Pugsley is new this year, so it has a smaller sample size.

Pugsley is running 12-13 psi (Nate front & rear)
Nail Trail is running 35-40 psi (Nokian Mount & Ground front; Continental Top Contact rear)

Jseis 

My all time fav. Has that Ruskie thing going. Hollow wheels are for vodka!

Jseis 

Salt & sand not a good mix which is why a rinse & blow dry after beach riding. Never-seize on all threads & particularly steel to aluminum threads 'cause dissimilar metals = galvanic corrosion. That means: Never.Ever.Coming.Apart.

I mi get the most sand/salt mix from splashing across streams, standing water on beach sand and that'll drip down on the chain...ugh.

SHOFINE

I think I bleed salt & sand!

Jseis 

Weathers been fab here too. 40 degree temperature shift from 71 F yesterday at 1-2 pm to 31 F this morning at 7 am.

tickyboy

Mind if I ask what it cost?

Thanks!

scottsmith

Not at all, it was about $780 after taxes & shipping. I signed up for a free trial of Amazon prime just to get free 2-day shipping on it.

Cheers

skijor

This guy is pogo-ing like crazy. Does he have insufficient tire pressure or is that just the nature of fatties?

SHOFINE

I've never ridden in the snow, but usually too much air causes it. This guy claims less than 1 lb in these tires.

bruised

I struggled with the pogo thing when I first got my bike. If you run 10+ psi it seems to be fine, lower psi's too. But there's a range in between where it can be an issue, particularly on flatter surfaces. It's easy enough to resolve, just shift up a gear and ride a lower cadence.

I wish I could pull a wheelie like that guy! I can barely get 2 inches off the ground.

SHOFINE

Before I got my Fatty I never thought too much about doing wheelies. I can't help myself from doing it now when I get on it. I feel like a clown on it!